1. Field of the Invention
This invention relates generally to wheelchairs, and more particularly to wheelchairs which are provided with a shock absorbing means. This device relates even more specifically to devices which can be attached to wheelchairs to provide them with shock absorbers.
2. Description of the Prior Art
Conventional wheelchairs normally include left and right closed frame members connected by diagonally extending crossed tubes arranged scissored together if the chair is of the folding type. Generally, the left and right closed frames include extending back uprights for supporting the chair back and forward upright extending tubes supporting the front of the seat, with the rear and forward uprights being connected by horizontal upper and lower arms to form the left and right structures. Left and right main wheels are rotatably mounted to the rear portion of the closed frames. These wheels are normally firmly attached to the uprights by means of a bolt which passes thrugh the wheel and through a wheelchair axle which is unitary with the wheelchair upright.
This construction works well for wheelchairs which are used in areas having flat floors. However, due to the fact that the wheels are firmly attached to the uprights of the wheelchair, no shock absorbing properties are imparted to the entire device. When traversing ground having uneven terrain in such a wheelchair, many difficulties arise. The ride experienced is at best uncomfortable and at worst can be dangerous since one of the wheels of the chair may actually leave the ground due to contact with bumps or small gullies. This situation may result in toppling of the wheelchair.
Known types of wheelchair suspension systems as exemplified by U.S. Pat. No. 3,917,312 to Rodaway are incorporated in the wheelchairs at the time of manufacture. While these suspension systems are reasonably effective, they provide no means to aid the person who owns a wheelchair which is purchased without such a system, unless he goes to the expense of purchasing an entire new wheelchair. These systems are also rather complex and add greatly to the cost of manufacture of the wheelchair.